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4 brick mini gas forge?

Discussion in 'Shop Talk - BladeSmith Questions and Answers' started by Hawk45, Jan 5, 2012.

  1. Hawk45

    Hawk45 Gold Member Gold Member

    Jan 28, 2005
    I've seen the 1 brick hollow micro forge and the two brick (one on top of the other wired together) hollow mini forge. Would it be possible to do a 4 brick (2x2 end to end) for longer blades? I imagine each would need its own heat source or would one central source work? Would an exterior sealant be needed? Thought about doing the 5gal bucket forge but its more volume than I would need.
     
  2. Bo T

    Bo T

    Feb 12, 2011
    I made the 1 soft brick forge and it seems good for heating about a 3" length of steel without moving it back and forth a lot. If you want to heat a longer piece of steel I think 2 burners would be better. I am considering something like this except using 2 sets of 6 bricks making a chamber 3" wide and 4.5" high and 18" deep and I could use the harder fire bricks. I am assuming your forge design is 4.5" wide by 6" high by 18" deep?
     
  3. tattooedfreak

    tattooedfreak Steel mutilater is more like it. Gold Member

    965
    Mar 12, 2010
    Instead of doing that why not switch to the coffee can forge? How long a blade are you trying to heat?
     
  4. Atlas Knife Company

    Atlas Knife Company KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Feb 16, 2010
    Have you considered how much metal you wish to heat up. With the exception of the heat treat you are usually only forging a few inches at a time.
    Here is the design of my two brick forge. Not wired together, but cut in half and stacked so the block is 4½ x 4½ x 12. Then, you drill a hole down the middle giving a 2½" chamber that is 12" long. I built a 21" long chamber, but with propane torches it needed four burners to heat the length of the metal and I quickly learned than on knife sized steel, you can only hammer so much before it cools off.
    new_two_burner.jpg

    I've got 782 more of these to experiment with so give me a design and I will try it. If you're in town, I'll give you a few to experiment with.
    firebrick.jpg
     
  5. Hawk45

    Hawk45 Gold Member Gold Member

    Jan 28, 2005
    Right now I'm not making huge of blades, but would like to make a few Bowie knives down the line. I'd say 12-15" max would be as long as I'd go. Width being no more than 3" probably. Just really looking for something cheap and efficient to make my HT easy. I'm just getting started as a hobby and don't want to drop a ton of money into a forge just yet. I'm just working with steel and files (no grinder yet).

    So here is what I was thinking:

    Block|Block
    Block|Block
    - so thick block on block (like a mini 2 brick forge) hollow out half of each block and stack. Then do the same with 2 more blocks. Then lay end to end. So essentially doubling the size of a mini 2 brick hollow forge.

    Thanks guys,
    John.
     
  6. woodwrkr221

    woodwrkr221

    391
    Jan 28, 2011
    It sounds to me as if you might need to use a steel angle frame to hold the blocks together and in line. Just a thought.

    Also would a 1 gallon paint can make an acceptable mini forge similar to the coffee can forge?
     
  7. insanity

    insanity

    392
    Feb 28, 2002
    Another option would be to use Insboard.

    Wayne Suhrbier
     
  8. Hawk45

    Hawk45 Gold Member Gold Member

    Jan 28, 2005
    I have an old wood burning stove that has insulation board on the sides and 1.5" thick white bricks (I'm guessing fire bricks) covering the board... but they are hard. Think I could use that material.
    Maybe just take that old thing and put some thermal blanket in it and stuff a burner in there and cover the front with some bricks? It's not that big.
     
  9. tattooedfreak

    tattooedfreak Steel mutilater is more like it. Gold Member

    965
    Mar 12, 2010
    Yes woodwrkr, a 1 gal paint can would be similar, just a little bit bigger. Obviously use the unused ones unless you can get all of the paint out hehe. If you do make a paint can/coffee can forge, you are better off using a refractory instead of insowool. They work really well for smaller pieces and with the right torch you can smelt small amounts of silver or gold.
     
  10. woodwrkr221

    woodwrkr221

    391
    Jan 28, 2011
    Thanks tatooedfreak, I'm assuming you are talking about cast refractory? I built a mini Zoeller style sidearm burner and I plan on using this for small fixed blades and maybe even slip joint folders someday. I also plan on inserting a ceramic TC either from the side or rear.
     
  11. Lone Goose

    Lone Goose

    8
    May 14, 2012
    Related question: I am also trying to build a small, very cheap first forge...The "soft" fire bricks are called "insulating" fire bricks..the hard ones are not usually called "insulating"...I can NOT find soft/insulating bricks around here, so I would have to order on line, and pay shipping for "bricks"...not a great idea. I can get hard bricks for less than $2 each locally. If I bought 10 bricks and built a little "oven"... would that work? I would be trying to heat with a standard plumbing type propane torch through a gap in the bricks or a hole drilled in one brick.

    Would the fact that they are not "insulating fire bricks" mean I would loose too much heat to the bricks to get my blades up to hardening temps? Will a propane torch build up enough heat inside that to harden the blades?
     
  12. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Several things:
    One. - mail is still delivered to NH...at least it was back in the 1950's when I lived in Meriden. Ordering a few soft fire bricks will be cheap and they will come to your door. Zaph, Hightemptools, many knife supply companies, and many refractory and pottery suppliers sell them.

    Two - NH has several suppliers that sell what you want. Google "Refractory suppliers in NH" and "Pottery suppliers in NH" for a start.

    Three - an all hard refractory oven will need a lot more heat supply, and an insulating jacket of wool and/or insuboard to work. Those type bricks are made to be fire resistant , not insulating. They will get hot all the way through. It would take a big burner and a long time to heat up. Once fully soaked, it would work, but for the money and difficulty, it would be far better to build a regular forge.

    Four - a small regular forge can be easily built for $70-100 or less. Since most cobbled together mini-forges cost around $50 and will do only very basic forging and really poor heat treatment, why not spend the extra few bucks and build a good tool you can use for the next ten years.

    Five - If the build of a burner and small regular forge is totally out of the question, a simple small forge can still be built from a paint can/#10 can/ stove pipe/gallon coffee can/rolled up piece of sheet metal/etc. Look for any metal cylinder that is about 6-8" diameter and 10-12" long.
    You will need a 12"X18" wide piece of 1" thick Kaowool and a pound of Satanite to line it. A JTH or similar torch can provide the heat source. Mapp gas is best for the fuel. I bet several folks on this forum would cut off a scarp of K-wool and scoop a baggie full of satanite and give it to you for the shipping. The New England Bladesmiths Guild and several other groups in your area have regular get togethers where I'm sure someone could hand you the box of materials for free. You will need to put a 1" hole through the tube and insulation about 2/3 the way back, for the torch or burner to stick in. Four fire bricks ( hard or soft) will make do for blocking off the back and front. This should cost about the same as a four brick forge and be much better.

    Six - when looking for fire brick, always ask for soft fire brick.
     
  13. Calvin Richardson

    Calvin Richardson

    377
    Oct 13, 2011
    Thanks for that Stacy. I'm wanting to build a small forge for myself and that sounds like just the ticket. Now would anyone care to donate to the furtherance of my meager education in the metal forming arts? Pretty please? With sugar on top?:D Will a small forge such as the can forge reach welding temps? I'm wanting to eventually got into cable damascus.
     
  14. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    A small forge with a torch as the heat source won't weld. If you build a burner, then it might work. The biggest problem will be in durrability of the forge when running at 2400+ F.
     
  15. Calvin Richardson

    Calvin Richardson

    377
    Oct 13, 2011
    Would the temp basically burn out the shell of the forge? I don't have enough money to pony up for a good forge. I would like to use propane but maybe charcoal would be cheaper.
     
  16. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    Welding is hotter and takes a better insulated forge than the bare minimum. If you build a blown forge, with a 2" high-Z will liner , satanite, ITC-100 and all, it is not a problem to weld up damascus billets. Otherwise., making damascus should be left for later on. It is not a cheap process anyway.
     
  17. Calvin Richardson

    Calvin Richardson

    377
    Oct 13, 2011
    :DThanks Stacy! You always give great advice. Is this true with cable as well? I'm assuming it would be. You're still performing a forge weld even if it is all the same material.
     
  18. Atlas Knife Company

    Atlas Knife Company KnifeMaker / Craftsman / Service Provider Knifemaker / Craftsman / Service Provider

    Feb 16, 2010
    If you are willing to meet me in Kansas City next weekend, I'll bring you a box of soft firebricks. Just PM me if you are interested.
     
  19. Stacy E. Apelt - Bladesmith

    Stacy E. Apelt - Bladesmith ilmarinen - MODERATOR Moderator Knifemaker / Craftsman / Service Provider

    Aug 20, 2004
    While cable is easier in some aspects ( no need to set up a billet) it is still welding.

    I don't think a torch will be hot enough for a weld. A venturi burner will do it if the forge is made to hold in enough heat. A blown burner welds very good.
     

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